Dash-pot.



Patented Apr. 8, |902.

No. @97,i45.

W. A. HEYWDD.

DASH POT.

(Application led Sept. 24, 1901.)

2 Sheets-Sheet I.

(No Model.)

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No. 697,145. Patented Apr. 8, |902.

W. A. HEYWOOD.

D A S H P 0 T.

(Application filed Sept. 2;, 1901.)

2 Sheets-Sheet .2.

(No Model.)

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Nrrnu STATES PATENT OFFICE;

IVILLIAM A. HEYIVOOD, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR OF ONE-HALF TO EDIVIN A. MOORE, OF PHILADELPHIA, PENNSYLVANIA.

DASH-POT.

SPEGIFIGATION forming part or Letters Patent No. 697,145, dated April 8, 1902.

Application filed September 24, 1901. Serial No. 76,354. (No model.)

To all whom, it 71mg/ concern,.-

Be it known that I, WILLIAM A. HEYWOOD, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Dash- Pots; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which `it appertains to make and use the same.

My invention relates to engine valve-gear of the Oorliss and trip-gear-valve types, has especial reference to dash-pots, and consists in certain improvements in dash-pots, which will be fully disclosed in the following specication and claims.

Considerable difficulty is encountered with the ordinary construction of dash-pots and their use in connection with engines subject to very variable loads in that in the varying cut-offs of the valves, caused by the varying loads on the engine, the movement of the dash-pot Varies accordingly, for the reason /wgtthat the dash-pot is directly connected to the engine-valve. This difticulty is chiefly with the vacuum or power part of the pot. If the lift of the piston is small, it produces a small vacuum, or if large it produces a very much better vacuum. With the cushion part of the pot adjusted to bring the valve to rest nicely-say at one-half the liftit is not suited for either the small or the large lift with an invariable discharge-opening for the air on the cushion part of the dash-pot, and as the load, and therefore the lift of the piston in the dash-pot, Varies it is necessary to adjust the discharge-opening by hand while the engine is running, giving the opening more or less area by either increasing or decreasing said opening as the lift increases or decreases. To overcome this difficulty, I provide a graduated openng in the dash-pot, regulated by the piston, which varies the discharge automatically and subjects the free end of the piston-rod of the dash-pot to a constant pressure, as will hereinafter more fully appear.

In the accompanying drawings, which form part of this specification, Figure 1 represents a side elevation of the upper end of a steamchest provided with my improved dash-pots. Fig. 2 represents the dash-pots detached, on an enlarged scale, one being shown in side elevation and the other in vertical longitudinal section; Fig. 3, an enlarged view of the outer end of the dash-pot; Fig. 4, an end View ofthe inner end ot' the cylinder; Fig. 5, a longitudinal section on line 5 5, Fig. 4:; Fig. G, a longitudinal section of the piston detached; and Fig. 7 a vertical transverse section of a Vacuum dash-pot, showinga modification of my invention.

Reference being had to the drawings and the designating characters thereon, 1 indicates a steam-chest cover of a Corliss type of engine provided with the usual valves, valveoperating rods, cranks, and the trip mechanism, neither of which forms any part of my present invention and being well known in the art require no elucidation.

2 indicates the cushioning-cylinder of the dash-pot, in which is formed a rabbet 3 to receive a sleeve 4, which surrounds the cylinder and lls the rabbet, is revolubly adj ustable thereon and secured in position when adjusted by a set-screw 5, and in the sleeve are one or more openings 6, preferably tapering or Wedge-shaped, the taper extending toward the outer end of the cylinder, and to reduce the clearance in the port 6 by reducing its depth the wall ot the cylinder 2 is provided with slots 7, which extend through the reduced portion 3 for the discharge of air from the cylinder through the opening 6 when the piston S is making its return stroke and cushioning the valve to which it is attached by its rod 9.

The piston is provided with feather-keys 10, which lit the slots 7 in the cylinder and ll up the clearance which would otherwise be formed by the thickness of metal in the wall of the cylinder, and the piston is secured. to the rod 9 by screw-threads 11 or in any preferred manner.

The heads of the cylinder are cast separate therefrom and secured thereto in the usual manner. In the outer head 12, through which the piston-rod. 9 extends, are formed rightangled ports 13 to admit air to the cylinder 2 to ll the cylinder and destroy the vacuum ,as the piston advances in its instroke as the valve to which it is attached is being opened by the valve-gear, and the ports 13 are controlled by ball check-valves 14, seated upon the upper end of the vertical part of the port.

As the dash-pots are provided for the valve at each end of the cylinder, they are preferably made in pairs, one opposite the other in the same plane, and by thus locating the cylinders the inner heads 15 of the two cylinders are cast in one piece with a neck 16 between them, and in this neck is formed a chamber 17 which is supplied with any fluid under pressure, such as steam from the engines source of supply or from a storagereservoir through pipe 1S, and the pressure of this fluid is exerted upon the end 19 of the piston-rod 9, which extends through the opening 2O in the cylinder-head 15 into said chamber and is provided with a packing 21 to prevent leakage of the fluid to the atmosphere through the cylinder 2, and the opening 2O is provided with a suitable lining 22 to receive the wear of the rod.

The piston S is supplied with a suitable lubricant through channel 23 and tube 24 from a cup, (not shown,) and the cylinder 2 is provided With an opening 25 for the escape of air during the instroke of the piston.

In Fig. 7 I have shown the application of my invention to the ordinary vacuum dashpot. The cylinder 26 is provided with the slots 27, the revoluble jacket 28, having the graduated openings 29, the air-supply ports 30, inwardly-openingvalves 31, a support 32 for the jacket, and a supplemental cylinder 33, in which the vacuum is created and is furnished with an outwardly-opening valve 34, and the piston 35 is provided with featherkeys 36, which engage the slots 27, and an extension 37, which is of the diameter of the cylinder 33 and against whose upper end the constant pressure of the atmosphere is eX- erted.

The operation is as follows: Vhen the valves are opened by the positively-connected valve-gear, the ends 19 of the piston-rods are projected into the chamber 17, the cylinder 2 is supplied with air through the ports 13 and valves 14, and when the valve-gear is released by the trip the valves are quickly closed by the pressure of the fluid' in said chamber exerted upon the end 19 of the valverod 9 and are brought to rest and cushioned by the piston 8 of the dash-pot cylinder 2, the discharge of the air from said dash-pot cylinder being regulated by the piston and the graduated opening or openings 6 in the sleeve 4 to produce a continuous cushion of the piston 8 and the valve to which it is attached throughout the entire stroke of the piston from the full stroke to the smallest movement of said piston and valve.

Having thus fully described my invention, what I claim is- 1. A dash-pot having a piston connected with a valve, a valve-actuating mechanism for moving the valve and the piston in one direction, means for applying a constant pressure to return the piston, and means for producing variable resistance to the return stroke of the piston.

2. Adash-pot having a piston, in combination with means for applying a constant pressure to one side of the piston, and means for producing variable resistance on the opposite side thereof.

3. A dash-pot having a cylinder provided with an opening in the wall thereof, and a revoluble jacket having an opening therein registering with the opening in the wall of the cylinder; in combination with a piston.

4. A dash-pot having a cylinder provided with a longitudinal slot in the wall thereof, and a revoluble jacket having an opening therein registering with said slot; in combination with a piston having a feather-key thereon engaging said slot.

5. A dash-pot cylinder having longitudinal slots in the wall of the cylinder, and a revoluble jacket having openings therein registering with said slots; in combination witha piston having keys thereon engaging said slots.

6. A dash-pot cylinder having longitudinal 9 slots in the wall thereof the length of the travel of the piston, and a revoluble jacket having a graduated opening registering with said slots; in combination with a piston having keys engaging the slots.

7. A dash-pot cylinder provided with a piston, and having induction-ports and valves in one head thereof, and an eduction-passage in the wall of the cylinder; in combination with means for regulating the discharge from the cylinder and producing variable resistance to the piston during its outstroke.

8. A dash-pot cylinder having a chamber at one end, means for supplying fluid to said chamber at a constant high pressure, and means for producing variable resistance in the dash-pot cylinder; in combination with a piston subject to said pressure and said resistance.

9. A pair of dash-pots adjacent and connected by the heads thereof, and a duid-pressure chamber in the neck between the heads; in combination with a piston in each pot having a rod extending into said chamber.

In testimony whereof I affix my signature in presence of two witnesses.

WILLIAM A. HEYWOOD.

Witnesses:

EDwD. P. HAINEs, C. W. METOALFE.

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IDSF.

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